The Problem

Multidirectional instability (MDI) of the shoulder is a difficult problem consisting of symptomatic inferior and anterior/posterior hyperlaxity. The mainstay of treatment is conservative management consisting of postural and periscapular stabilization rehabilitation exercises. For those patients who fail a trial of conservative management, both arthroscopic and open techniques have been described.

Clinical Presentation

The onset of instability symptoms may or may not be preceded by a traumatic event in patients with MDI of the shoulder. Patients may describe instability events occurring at mid ranges of motion that correspond with activities of daily living. These events will usually consist of multiple subluxation episodes as opposed to frank dislocations. Attention should be paid to the described positions of subluxation or dislocation. Abduction and external rotation may suggest an anterior instability component while elevation and internal rotation of the shoulder is more suggestive of posterior pathology. Reports of non-specific paresthesias are not uncommon secondary to the traction placed on the brachial plexus with heavy activity in the hypermobile shoulder and are usually seen secondary to an inferior instability component. Patients may report instability episodes in other body regions such as the patellofemoral joint or ankle.

Diagnostic Workup

Physical Exam

A generalized exam of the cervical spine and both shoulders should be performed. Active/ passive range of motion and strength of the affected shoulder should be assessed and compared to the contralateral side. The resting position of the scapula and any scapular dysrhythmia should be noted. Hyperlaxity may be present bilaterally and in several directions, but symptomatic instability on history and physical examination generally occurs mainly in one direction and is usually unilateral. Most patients will exhibit a positive sulcus sign (Figure 1) in addition to either a positive apprehension-relocation or posterior jerk test. The Gagey hyperabduction test can be used to assed for inferior laxity (With patient in the seated position and the shoulder starting in the adducted position, the examiner stabilizes the scapula with his or her forearm placed on top of the shoulder. The affected shoulder is abducted noting the range of abduction prior to motion of the scapula. Normal passive abduction is 105 degrees. Passive abduction greater than 105 degrees indicated inferior glenohumeral ligament laxity).

Figure 1.

The sulcus test is performed with the patient arm at the side and inferiorly-directed traction on the arm by the examiner at the elbow. A depression occurs below the acromion in patients with excessive inferior translation.

Patients may also commonly exhibit some of the signs of generalized ligamentous laxity (see Table 1).

Imaging

Radiographs should be obtained in patients reporting multiple subluxation or dislocation events to evaluate the glenoid and humeral head for bone loss. Radiographs will be normal in most cases. Magnetic Resonance Imaging with contrast (MRA) is the study of choice for the evaluation of MDI of the shoulder. Findings generally include a large capsular volume highlighted by a large axillary recess on coronal cuts.

Non–Operative Management

Conservative management should consist of a minimum of 6 months of physical therapy consisting of two phases: scapular stabilization exercises and rotator cuff proprioception and strengthening. Scapular stabilization is centered on isometric exercises augmented with bracing and taping if needed. Once improvements are seen in periscapular stabilizers and scapular mechanics, patients should be advanced onto exercises emphasizing rotator cuff proprioception and then strengthening.

Indications for Surgery

Surgery is indicated in patients who have undergone 6 months of dedicated physical therapy and still exhibit symptomatic glenohumeral instability in at least one direction with hyperlaxity on physical exam in at least two directions. Care should be taken to evaluate the imaging for any evidence of labral tearing/ degeneration, rotator cuff pathology and spinoglenoid cysts. Patients undergoing surgery should have a history negative for voluntary dislocation and must be willing to comply with post-operative immobilization and rehabilitation protocols.

Surgical Technique

Equipment/ Instrumentation

A traction attachment is needed for the operative table to facilitate traction on the operative arm. A bean bag is required for lateral decubitus positioning, and the surgeon should have available the instrumentation (drill guide, drills, suture passers) for their suture anchor of choice.

Set Up

All patients undergo a general anaesthestic following the administration of an interscalene block before being placed on a beanbag in the lateral decubitus position. An axillary roll is placed in the contralateral axilla and all pressure points are padded using a gel pad between the bed and the down knee and a pillow between the legs. An examination under anesthesia is performed first to identify the dominant patterns of instability and elicit the presence of a sulcus sign, clicking, or crepitus. After the examination under anaesthesia, pre-operative prophylactic antibiotics are administered and the patient is prepped and draped in the standard sterile fashion. Once the operative arm is covered to just below shoulder level with a sterile stockingette, it is placed in a traction holder that is secured to the table traction attachment with S-clamps. Ten pounds of traction is attached to the longitudinal traction pulley and a Velcro strap is used to attach the arm to the abduction traction pulley before placing ten pounds of weight on that pulley as well.

Procedure

Following sterile prep and drape, surgical landmarks are outlined on the skin and include the acromion, scapula, clavicle, and coracoid process. All potential portals sites are then injected with 0.5 % Marcaine without epinephrine and the arthroscopic procedure is initiated using a posterior viewing portal. The surgeon may note that it is exceedingly easy to advance the arthroscope between the glenoid and humeral head (Figure 2). A diagnostic arthroscopy is performed in standard fashion to evaluate the articular surfaces of the glenoid and humeral head, glenohumeral ligaments, rotator cuff, biceps tendon, rotator interval, capsule, and labrum. An anterosuperior portal is established just behind the biceps tendon with an anteroinferior portal being made just above the subscapularis tendon via needle localization. This affords anchor and suture placement in the anteroinferior quadrant of the glenoid. In some cases, a 5-o’clock portal placed percutaneously through the subscapularis tendon is needed to access the inferior labrum and capsule. When necessary, a posteroinferior portal is established at the 7-o'clock position for placement of posteroinferior glenoid anchors or sutures.

Figure 2.

A widened glenohumeral joint space with patulous capsule suggestive of MDI of the shoulder.

In the setting of MDI, there is generally extensive irregularity of the labrum consistent with circumferential tearing. Additionally, labral tissue may be absent inferiorly. All labral pathology is addressed surgically with the use of knotless suture anchors with interval capsular plication stitches using a synthetic monofilament suture. In our experience, capsulolabral pathology in the setting of MDI generally occurs in a 180 degree orientation from the 3 o’clock to 9 o’clock position, but it is not uncommon for these patients to exhibit 270 degrees or more of pathology.

A spectrum suture passer (Linvatec, Largo, Florida) is used to pass a synthetic monofilament suture as a shuttle stitch through capsule and labrum. This suture works as a shuttle to facilitate the passage of labral tape (Arthrex, Naples, Florida) through labrum and/or capsule. For posterior labral/ capsular pathology, knotless suture anchors are then sequentially placed from the posterior and 7 o’clock portals using the appropriate drill guide and drill. Visualization is achieved through the anterosuperior portal during this process. Labral tape should be brought out the same cannula through which the anchor was drilled and the suture ends are passed through a knotless anchor. The knotless anchor is then inserted into its pilot hole on the glenoid and the sutures are tensioned before final seating of the anchor and cutting of the free suture limbs. This process is repeated for each anchor.

Anterior labral/ capsular pathology is addressed in the opposite fashion by visualizing from the posterior portal while inserting sutures and anchors through the anterosuperior and anteroinferior portals. Based on surgeon preference, viewing may also be done through the anterosuperior portal while placing anterior suture anchors through the anteroinferior or 5 o’clock portal. Additionally, standard suture-based anchors may be used instead of knotless anchors if preferred. If this technique is desired (Figure 3, Figure 4, Figure 5, Figure 6), the anchor is placed first and one limb of suture is shuttled around the labrum and through capsule using a Suture Lasso (Arthrex, Naples, FL) or a shuttle suture that has been placed using a Spectrum (Linvatec, Key Largo, FL). Capsular plication sutures using a synthetic monofilament suture may be placed in between anchors to add additional stability.

Figure 3.

Viewing with the arthroscope in the anterosuperior portal, a standard suture anchor has been placed and an Arthrex suture lasso (Naples, FL) has been passed through capsule and around the labrum.

Figure 4.

A suture is shuttled around the labrum and through capsule using the Lasso.

Figure 5.

Knot-tying is done following suture passage.

Figure 6.

Final picture through the anterosuperior portal showing the inferior capsulolabral plication.

If needed, rotator interval closure is then performed to further decrease overall capsular volume based on capsular volume assessment following completion of the labral repair. If necessary, interval closure is performed while viewing from the posterior portal. A shuttle suture is passed through the superior and middle glenohumeral ligaments via either spinal needle or Spectrum through the anterosuperior portal. The PDS stitch is then used to shuttle a labral tape suture, which is then tied through the anterosuperior cannula to decrease capsular volume by closing down the interval between the SGHL and MGHL.

Pearls and Pitfalls of Technique

Pearls

Distraction of the humeral head away from the glenoid is better achieved with lateral decubitus positioning. This allows for better visualization of both intra-articular and capsular structures.

Have a wide variety of angled tips for the preferred suture passer. This will ensure the ability to pass sutures in any quadrant of the glenohumeral joint that requires labral repair and/or capsular plication.

If poor capsular tissue exists and its ability to hold a stitch is concerning, suture anchors may be placed in the glenoid with plication sutures incorporating both labrum and capsule.

Pitfalls

Ensure that surgical stabilization procedures are directed only towards the pathologic structures contributing to the patient’s symptomatic instability and not those contributing to asymptomatic hyperlaxity. Addressing all structures surgically may lead to overconstraint of the shoulder and loss of external rotation.

Exercise caution when passing sutures to plicate the capsule around the anteroinferior glenoid. The axillary nerve is in close proximity to the capsule in this region of the shoulder and can be iatrogenically injured while passing sutures with penetrating suture shuttling devices that are passed too deep.

Be sure to perform inferior capsular shifts anteriorly and posteriorly by placing sutures through capsule inferior to where the corresponding knotless anchor will be placed. This aids in eliminating the inferior instability component that is commonly seen in these patients.

Potential Complications

Care should be taken to ensure proper anchor drilling and implantation to avoid pull-out. Axillary nerve injury can occur if suture passing instruments are placed too deep when passing inferior sutures. If standard suture anchors are used, knots should be tied away from the glenoid face to avoid damage to the articular surface. An appropriate period of immobilization and graduated activity should be used post-operatively to help reduce the chance of redislocation or recurrent instability.

Post–operative Rehabilitation

Postoperatively, the patient's arm is placed in a sling in slight abduction and neutral rotation. The first 6 weeks of rehabilitation consist of isometric and grip-strengthening exercises. Light isometric exercises as well as active range-of-motion exercises with limits of forward flexion to 140 degrees, external rotation of 40 degrees with the arm at the side, and 45 degrees of abduction are implemented from weeks 6 - 12. At 3 months, rotator cuff, deltoid, and scapulothoracic strengthening exercises are gradually advanced as tolerated. Eccentric exercises begin at 16 weeks with a gradual return to throwing activities, sports, or heavy occupations when indicated at 6 months.

Outcomes/Evidence in the Literature

(This is an excellent Level V review that comprehensively covers the most up to date literature on open and arthroscopic management of multidirectional shoulder instability. The authors emphasize key diagnostic steps that are extremely helpful in the evaluation of these patients. They also discuss several surgical pearls, including a discussion on the controversial area of rotator interval closure. Recently reported outcomes are also discussed.)

(This paper is another excellent Level V review that provides a comprehensive summary of both open and arthroscopic management of multidirectional glenohumeral instability. The authors specifically discuss the comparable clinical outcomes with arthroscopic management as compared to open management. Perhaps most helpful is the discussion of balancing capsular plication/imbrication to address the capsular laxity/redundancy with maintaining motion and not overconstraining the shoulder.)

(This level V review focuses mainly on posterior glenohumeral instability, however a thorough discussion of multidirectional instability is provided. Provencher and colleagues provide a thorough review of glenohumeral biomechanics as they relate to instability, and as such provides a background for understanding the underlying pathology and determining the most appropriate treatment modality (often non-operative in the setting of multidirectional instability).)

(This is a Level IV study that evaluates the MRAs of patients with anterior, posterior, and multidirectional instability and compares them with 10 control patients. Five reviewers analyzed the MRAs for capsular length and area, as well as labral pathology. The results show that capsular elongation and laxity play a role in patients with MDI.)

(Pollock and colleagues conducted a long-term retrospective clinical outcomes study following patients undergoing inferior capsular shift for multidirectional instability. All patients had failed non-operative treatment including an exercise program. The authors performed a lateral-sided shift of the capsule, and if necessary, reattachment of the avulsed labrum, in all patients. At an average 61 months follow-up, 61% and 33% had excellent and good results, respectively, with an overall stability rate of 96%. Of note, of the 36 athletes in the study, 31 returned to sports, but only 25 were able to return to their preoperative level of participation.)

(Alpert and colleagues performed a retrospective review on 13 patients undergoing arthroscopic stabilization with labral repair for multidirectional instability with at least 270 degrees of involvement of the labrum. At an average follow-up of 56 months, the authors noted 2/13 with recurrent instability with 9/13 complete satisfied. The authors reported overall good results in 85% of patients, as determined by WOSI, ASES, SST, VAS, SF12, ROM, and Cybex strength testing.)

(This paper by Neer represents the “classic” milestone paper discussing patients with multidirectional instability treated with inferior capsular shift. In this retrospective review, Neer and Foster describe 40 shoulders in 36 patients with involuntary inferior/multidirectional instability treated with open capsular shift. The authors reported one patient with recurrent instability at 7 months. The strength of this paper is the excellent explanation of the pathology and treatment for MDI, as it provided the basis for the next several decades of literature on this topic.)

(The evaluation and treatment of rotator interval has been a tremendous source of controversy in patients with glenohumeral instability, and in particular, those with multidirectional instability. This is a Level III study that analyzes the MRAs of patients with anterior, posterior, and multidirectional instability and compares them with 10 control patients. Five reviewers analyzed the studies and recorded anatomic measurements of various aspects of the rotator interval. The authors found that the rotator interval distance between the supraspinatus and subscapularis tendons were nearly identical for all groups, including the controls. The authors concluded that additional study was needed to examine rotator interval insufficiency in patients with shoulder instability.)

(In this paper, Gartsman and colleagues perform an excellent prospective evaluation of 47 patients with multidirectional instability undergoing arthroscopic treatment. At an average 35 months follow-up, the authors reported successful results in 44 shoulders, but noted one patient with recurrent instability, one patient with loss of strength during sports, and two patients with pain that limited their ability to perform throwing activities. Overall, this is one of the earliest mid-term clinical outcome studies evaluating MDI and is a well-conducted study.)

(This Level V commentary by Robin R. Richards provides an excellent overview as to the current challenges associated with diagnosing and treating these difficult patients. Of utmost importance is the plea to the orthopaedic community to reach a consensus as to the actual definition of multidirectional instability. He elegantly describes several papers that discuss the controversial topic of “normal” laxity versus pathologic “instability.” Overall this is an excellent, short, easy-to-read commentary that highlights some of the controversy surrounding this difficult topic.)

Summary

Patients presenting with MDI of the shoulder present a difficult problem. Conservative management with scapular stabilization and strengthening remains the mainstay of treatment, but arthroscopic surgery can be beneficial in those patients who fail conservative management. Surgery should be directed at the specific areas of pathology identified on a focused physical exam, and generally consists of anterior and posterior labral repairs with capsular shifts and plication as necessary. Rotator interval closure may be performed if capsular volume remains increased after stabilization.

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